Video From Inside Columbine

The tragedy at Columbine High School is being relived through a chilling piece of videotape, CBS News Correspondent Bill Whitaker reports.

CBS News has been given surveillance video from the cafeteria where, minutes after gunmen Dylan Klebold and Eric Harris opened fire, panicked students ducked for safety beneath the tables.

Even in edited form, the video conveys the chaos of what occurred during the early moments of the April 20 spree. No amount of editing can change the disturbing facts, including the deaths of 12 students, a teacher, and the two gunmen.

The video was presented at a school safety seminar for law enforcement officials which was attended by CBS Affiliate KRQE in Albuquerque this week. "You'll see some faculty moving around, trying to find out what's going on, what to do next, then the evacuation starting," Dr. Van Romero, a vice president at New Mexico Tech, said during his narration of the footage. "This is the real thing."

"We don't believe that it should be shown, that people need to see it, that it's going to help in any way, shape or form," said Rick Kaufman, a spokesman for the Jefferson County schools.

Michael Shoels, whose son, Isaiah, was killed at Columbine, didn't see the tape but said he hopes the dramatic footage will open people's eyes to the tragedy.

"Maybe it's good that America can see the heinous crimes that went on up at that school," Shoels said. "People need to see what happened. Maybe if people saw it we could all learn from it."

No one was killed in the cafeteria. But the time-elapsed, edited video spanning about 25 minutes shows what school officials believe to be one of the gunmen diving out of the way moments before what seems to be one of their bombs explodes, filling the cafeteria with smoke. Later the second gunman enters, kneels, aims and fires. Authorities have said in the past that he apparently was aiming at a huge propane bomb that could have leveled much of the building.

Jefferson County Sheriff Steve Davis has always acknowledged the existence of this tape, but insisted it didn't help the investigation. On Tuesday the department said the tape is still considered evidence. "I mean, it still is evidence," Davis said. "But now that it's going to play on national television networks as news, I think that will open up at least that piece of it to be public record."

Dan Salamone, news director for the Albuquerque affiliate, KRQE, said the tape was in the public domain and said pulling it off the air would be unrealistic.

KRQE aired about 40 seconds of the nearly two minute tape on Monday newscasts. CBS ran a shorter version nationally Tuesday, as did other CBS affiliates.

"It was certainly our editorial judgment to run it. We think it has news value," said Kim Akhtar, spokeswoman for The CBS Evening News. She said the tapwas carefully edited and didn't show graphic violence.

In Grand Junction, KREX-TV news director Ellen Miller said the station will talk to school and law enforcement officials before making a decision.

"We are going to talk to school people and police people to see if they believe there is value for them to plan for school safety," Miller said.

"But from a blood and guts standpoint, there is really no reason not to [show it]," Miller said. "You can't see anyone shot and there are no bodies lying on the floor."

Others chose not to broadcast the footage.

"After weighing the journalistic merits of the tape, we have decided not to air it on our local broadcasts," anchorman Bill Stuart of KCNC-TV told viewers of Tuesday's 5 p.m. newscast.

Student Sean Graves, who was shot just outside the cafeteria and is partially paralyzed, decided against viewing the tape. He did homework in his room while the program aired.

But his mother, Natalie Graves, said she cried as she watched it in their Littleton home and felt "great sadness and horror."

"It's one thing to hear or read about it, and another thing to see it," she said. "I have to say, I wish it wasn't out. But I knew that it was going to come out. It was just a matter of time."

Eric Harris and Dylan Klebold wrote that they wanted to blow up their school. They didn't, but one spark-filled blast did set fire to the cafeteria, where repairs and paint have wiped the evidence away.

With so many questions about the tragedy still unanswered, law enforcement has viewed this tape to try to figure out what happened -- and try to make sure it never happens again.